The present invention relates to an adjustable height platform. More particularly, the present invention relates to an adjustable height platform used to support a bed mattress, such as a hospital bed.
There are significant safety concerns for hospital and nursing home patients, especially elderly patients, associated with falling out of a bed. One approach to addressing the problem is by the use of guard rails on the sides of beds. However, the guard rails present their own risk of injury; for example, appendages may become caught in the space between the guard and the mattress. Belts or tie-down straps have also been used to keep patients from falling out of beds, but have been considered cruel and inhumane. Additionally, some states do not permit belts or tie-down straps to be used in nursing homes.
To overcome the problems associated with the use of guard rails, belts, or straps, some nursing homes have been known to place the mattress of the bed on the floor. This minimizes the distance that a patient would fall if he or she were to roll out of bed and thereby decreases the risk of injury to the patient. However, placing mattresses on the ground makes it very difficult for nurses, doctors, and other caregivers to assist or provide treatment to the patient. Medical personnel working with patients whose mattresses remain on the ground must constantly bend down and over to provide care. As a result, they suffer back injuries, pain, and muscular damage. Additionally, placing mattresses on the floor makes it awkward and uncomfortable for patients to get up from the mattress to stand up or transfer to a chair, wheelchair, or another bed.
Most known hospital beds are able to raise and descend. However, their range of motion is limited. There is no known bed support system capable of lowering to virtually floor level to reduce the risk of injury to patients from falling from a bed while unsupervised, and yet be capable of being raised to a height so that caregivers can tend to the patient from a comfortable, standing position.
The bed described in U.S. Pat. No. 5,090,070 to Heinz has a minimum height of approximately ten inches, or nearly a foot off of the floor to the top of the mattress support platform. Once a mattress is placed upon the bed frame described in Heinz, the top of the mattress would be approximately a foot and a half off of the ground. This height defines the distance a patient may possibly fall before hitting the floor.
Known collapsible beds are not able to lower the bed frame or mattress platform any further than approximately the ten inches disclosed in the Heinz ""070 patent. This is due mainly to the clearance required below the bed to house the actuators or drive cylinders used to raise and lower the bed frame.
For example, Bish et al., in U.S. Pat. No. 5,613,255, teaches a bed employing a scissors lift linkage actuated by a hydraulic or air cylinder. As a result, Bish requires significant clearance to house the actuator, thereby limiting the level to which the bed frame can be lowered with respect to the ground. Of course, a pit, much like a mechanic""s service pit, could be created beneath the bed to provide the required clearance for the drive mechanism and allow the bed frame to be lowered very close to the floor. However, such a design poses the risk that an appendage of the patient, medical personnel, or visitor may be caught between the bed frame or support lift and the ground as the bed frame is lowered into the pit. This technique would also be cost prohibitive and limit the mobility of the beds. Further, use of hydraulic fluid or air pressure to drive the actuators or drive cylinders may also be undesirable because highly pressurized fluid or air may pose a risk of damage to nearby objects and persons.
There is no known adjustable-height platform, which uses a scissors assembly, that can collapse completely flat without requiring a significant amount of clearance under the bottom platform to house the actuator or drive mechanism that lifts the bed. When a scissors assembly is completely lowered so that it is in a locked position with its legs aligned in the same horizontal plane, there is no prior solution that uses a horizontal force by itself to unlock the scissors assembly. Rather, known prior art beds use an actuator underneath the bottom platform to provide a vertical force on the legs of a scissors support system to break their initial alignment and unlock the aligned legs. This solution, however, requires clearance for the vertically oriented actuator, as discussed above. Such a clearance requirement significantly limits the level to which the bed can be lowered and prevents a scissors type support system from completely collapsing on itself or collapsing to virtually ground level. An alternative solution is to use a bed that does not collapse completely; however, this solution would leave the bed in a semi-raised position and at an unsatisfactory height above the floor.
There is thus no known bed support system which can be lowered to virtually ground level, and that can also be raised to a sufficient height to allow medical personnel to provide assistance at a comfortable height.
The present invention comprises an adjustable height platform system that can function as a bed frame. The system is self contained, and the bed frame can be raised to a height that facilitates medical procedures and treatment. The frame can also be lowered to only a few inches above the floor surface.
The bed frame of the present invention comprises a bottom platform, a top platform, and a scissors linkage coupled between the bottom and the top platforms. The scissors linkage includes scissors legs which pivot about a pivot axis. A drive system provides a horizontal force to the scissors linkage. An unlocking mechanism lifts the pivot axis in response to the horizontal force and unlocks the scissors legs from a collapsed, retracted, and aligned position. After unlocking the legs, the horizontal force continues to raise the top platform with respect to the bottom platform. As the drive system reverses direction and releases the horizontal force provided to the scissors linkage, gravity causes the scissors linkage to collapse and lowers the top platform. At a lowest position, the top platform rests on top of the bottom platform with the scissors linkage, the projection, and the unlocking mechanism being self-contained between the top and the bottom platforms.